Eric Kriss' work on Jelly Roll Blues is his own 1974 transcription.To quote him from page 6 of Barrelhouse & Boogie piano by Eric Kriss

Finally a word about the twenty-two transcriptions. Every attempt has been made to faithfully duplicate the original music on record within the limited boundaries of musical notation. Some of the rhythms and phrases are so idiosyncratic that a precise transcription would be hopelessly complicated. Accord­ingly, I have tried to find the right balance between accuracy and practicality. Thetranscriptions are intended only as guides to playing piano blues and the original recordings must be religiously consulted to master the nuances and complexities of this rich piano tradition.

On the Jelly Roll Blues itself he says on page 8

Many recorded versions of the piece exist; the one transcribed here was taken from a piano roll made by Morton in 1924 and is currently available on Biograph BLP-I004Q.

Can I assume that, like Zimmerman's transcription, Eric Kriss' transcription would be public domain in the EU only?

The other edition of Jelly Roll Blues from Contemporary Jazz Giants : Jazz Class. Piano Solos. Publisher: Hansen House (1963) appears to be a good piano transcription of the Jelly Roll Morton's Red Hot Peppers band playing the piece. The same edition of the piece appears for sale online on various sheet music sites where it is possible to see the first page e.g. https://www.sheetmusicdirect.com/se/ID_No/89837/Product.aspx These pieces for sale say Copyright 1992 Hal Leonard at the bottom.But I assume that, despite this copyright of an online engraving by the Hal Leonard people, this edition may well be out of copyright as this is why Hal Leonard are able to stamp their own copyright on their engraving. There is no indication of it being edited by any named individual in the Contemporary Jazz Giants book nor the online sheet music sales sites.

Can I assume that this edition that I have as a scan from Contemporary Jazz Giants : Jazz Class. Piano Solos has a copyright status similar to that of the edition already uploaded and available on IMSLP?

This is rather complicated area of copyright. On the one hand, Morton's 1924 recording is free and clear in Canada and the EU while it's still tied up (until possibly 2067) in the USA. Ironically, Kriss' transcription from the recording would be unlikley to qualify as an arrangement or derivative work in the USA due to the hugh threshold of originality. This is also probably the case in Canada (who also enjoys a high originality threshold). The EU is possibly a problem from the standpoint of Kriss' notation being counted as an arrangement or at the very least a 'scientific edition' (= 25 years from publication). I'll have to consult the local library's copy of Nimmer on Copyright to see if they have covered any rulings on the issue.